He said: “I think some of that criticism is really quite unfair actually, because I know it’s a single missing child, but there are millions of British tourists that go to the Algarve, year-on-year, and essentially you’ve got a British subject who was the subject of a crime.

“There were other crimes that came to light following Madeleine’s abduction, that involved British tourists, so I think prosecuting it (the investigation) to a reasonable end is what you would expect.”

He added: “Others within law enforcement have made it very clear, this type of stranger abduction is exceptionally rare actually and we need to put it into perspective and it’s partly why Madeleine’s case is attracting so much attention, thrown in with many other ingredients, but this type of abduction is exceptionally rare.”

Kate McCann said she “used to feel really embarrassed when people used to say about the amount of money”, but added that “other big cases, like Stephen Lawrence, these cases cost a huge amount of money”.

Mrs McCann added: “I guess the one thing, because you always do feel guilty as the parent of a missing child - that other families haven’t had the publicity and the money, and I know there’s reasons why that happened, but I guess the positive is that it has certainly brought the whole issue of missing children to the forefront and I think people have benefited in many different ways, really.

“Because of that. I know the charity Missing People has had a lot of attention, haven’t they and all the families have come together I think it’s just highlighted it, made people more aware, and those families have had more support from each other.”

Around 30 British detectives were working on the UK side of the investigation into Madeleine’s disappearance, known as Operation Grange, when it was established in 2011.

The team has now been scaled back to four detectives.

Officers have sifted through some 40,000 documents and looked at more than 600 individuals since 2011.